US2362806A - Frequency modulation receiver - Google Patents

Frequency modulation receiver Download PDF

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US2362806A
US2362806A US484718A US48471843A US2362806A US 2362806 A US2362806 A US 2362806A US 484718 A US484718 A US 484718A US 48471843 A US48471843 A US 48471843A US 2362806 A US2362806 A US 2362806A
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frequency
signal
potential
resistors
channel
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US484718A
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Robert B Dome
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General Electric Co
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General Electric Co
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Priority to BE479153D priority Critical patent/BE479153A/xx
Priority to BE482547D priority patent/BE482547A/xx
Priority to CA432262A priority patent/CA432262A/fr
Priority to BE479154D priority patent/BE479154A/xx
Priority to FR961086D priority patent/FR961086A/fr
Application filed by General Electric Co filed Critical General Electric Co
Priority to US484718A priority patent/US2362806A/en
Priority to GB7770/44A priority patent/GB594769A/en
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Publication of US2362806A publication Critical patent/US2362806A/en
Priority to US567110A priority patent/US2422513A/en
Priority to FR938602D priority patent/FR938602A/fr
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
    • H03D3/02—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal
    • H03D3/06—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators
    • H03D3/08—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators by means of diodes, e.g. Foster-Seeley discriminator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
    • H03D3/02—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal
    • H03D3/06—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators
    • H03D3/08—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators by means of diodes, e.g. Foster-Seeley discriminator
    • H03D3/10—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal by combining signals additively or in product demodulators by means of diodes, e.g. Foster-Seeley discriminator in which the diodes are simultaneously conducting during the same half period of the signal, e.g. radio detector
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/22—Automatic control in amplifiers having discharge tubes
    • H03G3/26—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise, e.g. squelch systems
    • H03G3/28—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise, e.g. squelch systems in frequency-modulation receivers ; in angle-modulation receivers

Definitions

  • My invention relates to frequency-modulation receivers and more particularly to improvements in detectors or demodulators for frequency modulated carrier waves.
  • detector or demodulator circuits which are currently in-common use for the detection offrequency modulated carrier waves possess a tuning characteristic which exhibits three definitely distinguishable maxima of signal response. That is, as the channel is tuned through a fairly good signal is first observed, then a period of high distortion, then a range of good reception, then a second period of high distortion, .then a second period of fairly good reception, and finally the signal fades out. While it is well known to those skilled in the art that the central of these threema'xima is the optimum tuning position, it is also well recognized that this characteristic is confusing to unskilled operators who are not familiar with the cause of the three maxima and therefore unable to select'the proper tuning position.
  • This tuning characteristic whereby three maxima in signal response are presented is a function of the relative values of the resonant frequency of the signal channel and the mean frequency of the frequency modulated carrier wave being transmitted through the channel. Accordingly, the same characteristic will be observed in sets where the resonant frequency of the channel is to be tuned to the mean frequency of the incoming carrier and also in superheterodyne sets in which the mean intermediate frequency is to be tuned to the fixed resonant frequency of the intermediate frequency channel. It will be evident from the following description that my invention avoids both the distortion and the maxima of signal response on both sides of the optimum tuning position.
  • the channel is tuned through, for example, in y I ducing distortion-in its output.
  • I provide a discriminator circuit comprising a pair of diode rectifier circuits interconnected to provide in-phase signal voltages at selected points in the circuits.
  • the signal voltages thus obtained are supplied through a pair of parallel connected channelseparating electric discharge devices to a suitable signal reproducing device such as a headphone, loudspeaker, cathode ray tube or the like.
  • a suitable signal reproducing device such as a headphone, loudspeaker, cathode ray tube or the like.
  • Figs. 2, 3 and 6 are graphical representations of certain of the electrical characteristics of my discriminator;
  • Fig. 4 is a graphical representation of certain of the characteristics of a conventional frequency invention to pro- I discriminator upon which my invention is an improvement; and
  • Fig. is a schematic circuit diagram of a frequency modulation discriminator embodying my invention in a modified form.
  • a fre quency modulation receiver preferably of the superheterodyne type, which is essential to a full understanding of the invention.
  • the circuit shown at Fig. 1 is. that portion of a frequency modulation receiver which serves to derive, from a carrier wave modulated in frequency about a mean frequency in accordance with a desired signal, a signal voltage proportional in instantaneous magnitude to the instantaneous deviations of the carrier from the mean frequency.
  • the receiver comprises an electric discharge device III which may serve either as the last intermediate frequency amplifier, or, if desired, as a limiter.
  • the discharge device Ill comprises an anode and a cathode connected to an output circuit including the primary winding II of a discriminator input transformer which is tuned to resonance at an intermediate frequency by a suitable shunt capacitor I2.
  • I cludes a control. electrode or grid I3 which is arranged to be connected to a suitable source Illa of frequency modulated carrier waves.
  • a source of waves may be the intermediate frequency channel of a superheterodyne radio receiving apparatus, and the signal modulation may represent music, voice or the like.
  • the intermediate frequency channel Illa is provided with suitable manually controllable tuning means Illb for adjusting the mean frequency of the intermediate frequency carrier wave to a desired value. It is understood that when the tuning is correct for optimum response the mean frequency of the carrier coincides with the resonant frequency of the channel.
  • a superheterodyne receiver such a receiver commonly comprises a signal channel tuned to a fixed intermediate frequency, such as 2 to 5 megacycles, and including suitable amplifying and limiting devices preceding the discharge device I0. It will be understood that in a superheterodyne receiver the incoming frequency modulated carrier wave at radio frequency, for example 42 to 50 megacycles, is reduced in frequency by mixing the frequency modulated carrier wave with an unmodulated wave from a local oscillator to obtain a signal modulated intermediate frequency carrier wave at the difference frequency.
  • Tuning of the set to receive carrier waves of different radio frequencies is effected by changing the frequency of the local oscillator so that the difference frequency between the received carrier .and that of the local oscillator is made equal to to a pair of secondary windings I 4 and I5, and
  • the high potential terminal of the primary winding II is electrically connected to the adjacent inner or low potential terminal of the secondary windings I4 and I5 through suitable coupling
  • the discharge device II! also indifference of potential with respect to their midpoint, the polarities of the outer terminals being capacitors I6 and II respectively.
  • the secondary windings I4 and I5 are tuned as a unit to the intermediate frequency by means of a shunt capacitor I8. since at any instant the outer ends of the windings l4 and I5 are at the greatest opposite with respect to the mid-point, the outer ends will be hereinafter referred to as the high potential terminals of the secondary windings.
  • Each secondary winding I4 and I5 of the discriminator input transformer is connected to a series diode rectifier circuit comprising a twoelement electric discharge device, a load resistor and an intermediate frequency choke coil connected in series circuit relation.
  • the high potential terminal of the secondary winding I4 is connected to the anode I9 of a diode 20, the cathode 2
  • the other rectifier circuit is oppositely connected in that the low potential terminal of the secondary winding I5 is connected through an intermediate choke coil 25 and a pair of load resistors 26 and 21 in series circuit relation to the anode 28 of a diode rectifier 29, the cathode 30 of which is connected to the high potential terminal of the secondary winding I5.
  • the resistors 22 and 21 are of equal resistance, and the resistors 23 and 26 are of equal resistance. Preferably, the resistances of all four resistors are equal.
  • the common terminal of the resistors 22 and 23 is connected to the common terminal of the resistors 26 and 21 and grounded at 3!.
  • of the diode 20 and the anode 28 of the diode 29 are bypassed to ground for intermediate and higher frequencies by capacitors s2 and 33 respectively.
  • the induced voltages in the transformer secondary windings I4 and I5 remain equal and opposite but are shiftedin phase with respect to the primary voltage applied to the secondary winding midtap, the direction of the phase shift depending upon the direction of the instantaneous frequency deviation of the carrier wave.
  • signal modulation of the carrier wave changes in opposite vsenses the instantaneous magnitudes of the net voltages supplied to the diode circuits, the direction of the frequency deviationdetermining the direction of the'voltage change.
  • the instantaneous scalar magnitudesof the rectified currentsin the load resistors 22 and 21 vary in opposite senses at the signal frequency of modulation-of the carrier wave, thereby to give rise to signal frequency components of voltage across the resistors 22' tube 45.
  • the midpoint of the resistors 55 and 55 is connected through a high resistance grid leak resistor 58 to the grid 42a of the channel-separating discharge device 44.
  • the signal voltages appearing across the load resistors 22 and 21 are tapped at suitable points, as by potentiometer arms 40 and 4
  • the blocking capacitors 42 and 43 remove the unidirectional components of the signal voltages shown at Fig. 2 and apply to the grids 42aand 430. only the in-phase alternating components of the signal voltages.
  • The. electric discharge tubes 44 and 45 eachincludes a cathode 46 and an anode 41.
  • the cathodes 45 are connected together and to ground through a grid bias resistor 48 and a signal frequency bypass.
  • con- .denser 49 in parallel circuit relation.
  • the anodes 41 are connected together-and through a load resistor 50 to the positive terminal of a. suitable source 01 directelectric current supply, such as a battery 5
  • both sides of the optimum tuning position are avoided by providing suitable biasing potentials for the control electrodes 42a and 43a of the discharge devices 44 and 45 respectively.
  • the electrically remote terminals of the load resistors 22 and 21 are interconnected through a pair of serially connected and preferablyequal voltage dividing resistors and 54.
  • the electrically remote terminals of the resistors 25 and 20 are interconnected through a pair of serially connected and preferably equal voltage dividing resistors '55 and 55.
  • the midpoint of the resistors 53 and 54 is'connected through a highresistance grid leak resistor 51 to mum of the channel-separating discharge v15 rents in the circuits of the diodes 20 and 29 are equall and flow in opposite directions with respect to ground through the load resistors 22 and 21.
  • should be positioned upon the loadresistors 22 and 21 at points of equal potential above and below ground potential, respectively.
  • themidpoint of the resistors 53 and 54 and the mid- P int of the resistors 55 and 58 are both at ground potential and thus exert no biasing effect upon the grids 42a and 43a. Therefore, under the conditions described above the channel-separating triodes 44 and 45, being unbiased, provide parallel paths for the passage of a predetermined'dir'ect current through the signal output resistor 50.
  • signal modulation in the opposite'sense produces an in-phase change in potential at the brushes 40 and 4
  • the signal fre-' developed is supplied to they quency potential thus grids 42a and na-of the channel-separating discharge devices 44 and 45, respectively, and produces in-phase' changes at signal frequency in the instantaneous value of current passed'through' both of the devices 44 and 45. Since these devices are connected in parallel circuit relation,-
  • nodes and 4-5 serve as amplifiers of the signal, voltage as well as serving as channel-separators in a manner at. signal frequency in the resistor 55 producesacross the resistor a voltage at slgnalfrequency which maywhich will be hereinafter described.
  • the alternating component current be applied to any suitable signal reproduc l device.
  • I have shown a lead 60 connected to the high potential side of the load resistor 50 through a suitable blocking capacitor ii.
  • the capacitor 69 serves to separate the unidirectional and alternating components of the current through the resistor t, so that the signal voltage appearing at the terminal 60 the signal response upon opposite sides of thecorrect tuning position, I have shown at Figs. 3 and 4 a group of curves graphically illustrating certain characteristics or a balanced double diode discriminator in which the signal voltage is taken oif directly across equal portions of the diode load resistors.
  • Fig. 3 is shown a pair of voltage characteristic curves E; and E2.
  • the voltage E1 may represent the drop across the load resistor 22 of Fig. l as the carrier frequency deviates from the center or mean frequency F0
  • the voltage E2 may represent the voltage drop across the resistor 2'! as the carrier frequency deviates from the mean frequency F0.
  • any modulation of carrier frequency either an increase or a decrease in instantaneous frequency,,-produces a decrease in the instantaneous magnitude of signal voltage.
  • Such a condition produces maximum distortion in thesignal output.
  • the curve E. of Fig. 4 is characterized by substantially linear portions on each side of the maximum and minimum points as the signal voltage fades out. These small linear portions produce undesired rna ximav in the signal response upon opposite sides of the center frequency.
  • the side band distortion and undesired maxima in signal response on opposite sides of the proper tuning position are avoided by-biasing toward cutoff that one of the channel-separating amplifying tubes 44 and 45 which is associated with the dioderectifier producing distortion.
  • the diode rectifier producing distortion is thatone which is conducting the greater, and particularly a maximum, unidirectional current component. It will be. recalled that to provide demodulation the grids of the channel-separating amplifying tubes 44 and 45 are controlled by in-phase Signal notchtials obtained from the load 'resistor 22 and 2?.
  • the resistors 22 and 21 are not connected in balanced or back-to-back relation to provide the characteristic of Fig. 4, but are so connected that the direct current components of rectified currentflowing through these resistors flow in opposite directions with respect to ground.
  • the resistance of the resistor 58 is so high that the alternating component of potential appearing at the midpoint of the resistors 55 and 56 upon signal modulation of the carrier wave is sufiiciently attenuated so that substantially no alternating current component appears upon the grid 42a.
  • the amplifying discharge device 44 is substantially disabled whenever'the direct current component of rectified current through the diode 20 is in the region of its maximum value, and almost the entire audio response is conducted through the channel-separating amplifier 45.
  • a like eflEect-in lesser degree is present whenever one diode rectifier circuit conducts a greater unidirectional component than the other circuit, even though the unidirectional component does not attain its maximum value.
  • This positive biasing potential uponthe grid 63c increases the conduction of the tube 45 to compensate forthe decreased conduction of the tube 44.
  • the unidirectional. components of potential at the electrically remote terminals of the resistors 22 and 21 are unequally spaced with respect to ground. Specifically; the positive terminal of the resistor 22 is higher in unidirectional potential above ground than is the negative terminal of the resistor 21 below ground. Therethat distortion of the audio output will not result from driving the positively.
  • biased channel- 7 a predetermined limit the positive peaks of thefore,'the midpoint of the resistors 58 and 84 has a net positive unidirectional component of potential which is superposed upon the grid 48a of the device 48 through the high resistance resistor 81.
  • the resistor 81 is of sufficiently high resistance to attenuate any alternating components of potential and prevent their reaching the grid 48a; In this manner the conduction through the undistorted channel-separating t iode 48 is increased upon decrease of conduction through the distorted triode '44; By thus maintaining the total current through the signal load resistor 88 substantially constantdecrease in the volume of the signal upon the occurrence of a cutoff bias in one of the channel-separating tubes is avoided.
  • the cathode resistor 48 provides protection against suchexcessive positive bias. For example, let it be assumed that the triode 48 is biased positively. This causes the direct component of the plate current to increase, thereby causing the potential drop across resistor'48 to increase. The direction of the potential across resistor 48 is such as to give negative bias to the grid of triode; hence, the net bias on the grid does not increase as fast as the positive potential applied from the Junction of resistors 88 and 54 increases The 'cifect of this degenerative action on bias changes is to greatly extend the bias variations tolerable before grid current flows.
  • the discharge device 12 is preferably either the last intermediate frequency amplifier stage or the limiter stage of a frequency modulation radio receiving apparatus of the superheterodyne type.
  • the discriminatortransformer 18 is similar to the discriminator transformer shown in Fig. 1 and comprises a pair ofsimilar'secondary windings I4 and I5 having their inner or low potential terminals connected to the high potential terminal of the primary winding 'i'l' through suitable coupling capacitors I8 and I1, respectively.
  • the secondary windings I4 and 15 are tuned as a unit to the resonant frequencyof the intermediate frequency channel by means of a shunt capacitor 18.
  • the discriminator transformer secondary windings of Fig. 5 are connected to a pair of diode rectifier circuits in the same'manner as previously described in connection with Fig.”1. Specifically, the high potential terminal of the winding 14 is connected to an anode 18 of a'diode 80,
  • of which is connected through a pair of serially connected load resistors 82 and 88 and a high frequency choke coil 84 to the low potential terminal of the winding 14.
  • the high potential terminal of the secondary winding I5 is oppositely connected to the cathode 85 of a diode 88, the anode 81 of which is connected through a pair of serially connected load resistors 88 and 88 and'through a high frequency choke coil 88 to the low potential terminal of the winding 18.
  • the midpoint of the resistors 82 and 83 is connected to the midpoint of the resistors 88 and 88 and to ground at 8
  • the load resistors 82 and 88 are of equal resistance, and the resistances of the load resistors 88 and 88 are likewise equal.
  • the resistors 82 and 88 are by-passed for intermediate frequencies by condensers 82a and 88a, respectively.
  • the in phase signal potentials appearing at similar electrically spaced points of the resistors 82 and so are tapped oil through suitable potentiometer brushes t2 and 93 and supplied through direct current blocking capacitors 94 and 95, respectively, to a pair of channel-separating diodes 98 and do.
  • the brush s2 is connected through the condenser so to the anode 96 of the diode- 98, and the brush is connected through the condenser to to the cathode ill of the diode 99.
  • the diode so includes a cathode lilo which is connected directlyto an anode illfl oi the diode i353 and through asuitable blocking capacitor it? to the control electrode or arid oi acuitablesisnal amplifying discharge device tile,
  • the amplifying device its includes also a cathode lilo which is connected to ground and through a grid leak resistor lilo to the grid ltd.
  • the anode till oi the discharge device ltd is connected through a signal output resistor l to the positive terminal or a suitable source oi unidirectional current supply, such as a battery we.
  • a suitable source oi unidirectional current supply such as a battery we.
  • the signal frequency component of potential appearing across the resistor lot may be supplied through a suitable blocking capacitor lid to any signal reproducing device such as a headphone, loudspeaker or thelik 1
  • the usual distortion and undesired momma of signal response on both sides of the optiin tuning position are avoided by providing suitable differential biasing potentials ior the anodes and cathodes of the channel separating w discharge devices to and so.
  • the electrically remote terminals of the load resisters $32 and 88 are connected, respectively, through high resistance resistors iii and H2 to the cathode 500 oi the channel-separating diode 9E and to the anode it! of the diode so.
  • the electrically remote terminals of the load resistors 83 and 89 are interconnected through a pair of voltage dividing resistors i it and i M, the midpoint of which is connected through high resistance resistors anode 96 of the diode 95 and to the cathode 91 of the diode 99.
  • the resistors ill, 2, H5 and I I6 are of sufllciently high resistance to attenuate any alternating components of potential which may be impressed upon them from the diode rectifier circuits.
  • the separating diode 98 is biased further toward cutofi and the conductivity oi the diode 99 is further increased by impressing a. suitable potential upon the anode of the diode 98 and upon the cathode fill oi the diode 99.
  • This potential is derived from the midpoint of the voltage dividing resistors H3 and III which are connected between electrically re- 'mote terminals 01' the load resistors 33 and so.
  • the direct current component of current in the load resistor 88 is greater than normal,as assumed, the negative potential of the low potential terminal of the resistor 88 is greater than normal and the positive potential 01' the high potential terminal ottheresistor 89 is less than normal.
  • a discriminator for electric oscillations means for supplying a carrier wave signal modulated in frequency about-a desired mean frequency, means including a pair of rectifier circuits for deriving from said carrier wave signal potentials having mean values varying opposite- 1y and linearly in intensity within a predetermined range of frequencieswith variation of said carrier frequency from said mean frequency and having peak values of intensity at the limits of said range, means including a pair of signal channels controlled by said signal potentials respectively, and means for reducing the 'transmission of one or the other of said channels when the mean value of the controlling signal potential attains an intensity in the region of its peak value.
  • a pair of unilateral conducting devices a source of oscillations having its frequency modulated in accordance with desired signals about a desired average frequency, means tuned to said average frequency for supplying said oscillations to said unilateral conducting devices with intensity varying oppositely on said two devices with variations in the frequency of said oscillations whereby currents flow in said devices varying oppositely in intensity and at signal frequency as the frequency of said oscillations varies, an output circuit, a pair of electron discharge devices, means for supplying the signal frequency variations in current flowing through saidunilateral conducting devices through a respective one of said pair of electron discharge devices to said output circuit in aiding relation, and means responsive to variations between the average frequency of said wave and the frequency to which'said first means is tuned to decrease the conductivity of one or the other of said electron discharge devices in dependence upon the direction of said variation.
  • a pair of unilateral conducting devices a source of oscillations signal modulated in frequency about a desired mean frequency, means tuned to resonance at said mean frequency for supplying to said devices oscillations from said source varying oppositely in intensity with frequency modulation of said oscillations, a signal channel having a separate portion associated with each of said devices, means including said devices for supplying to said portions of said channel in-phase potentials at signal frequency to control said channel, and means responsive to a variation between said mean and resonant frequencies for reducing the transmission of one or the other portions of said channel in dependence upon the direction of said variation.
  • a pair of unilateral conducting devices a source of oscillations signal modulated in frequency about a desired meanfrequency, means tuned to resonance at said mean frequency for supplying to said devices oscillations varying oppositely in intensity with frequency modulations of said oscillations about said mean frequency whereby currents varying oppositely in intensity with said modulations flow sistors be selected for deriving the desired bias through said devices, a signal channel including a pair of electric discharge devices, means for supplying to said discharge devices in-phase control potentials at signal'frequency derived from signal modulated in frequency about a desired mean frequency, means tuned to resonance at said mean frequency for supplying to said circuit oscillations from said source varying oppositely in intensity with frequency modulations of said oscillations about said mean frequency, said load resistors being arranged to derive'thereacross inphase potentials of signal frequency, a pair of electric discharge devices having a common output circuit, means for applying said signal potential to said discharge devices respectively to control said output circuit, and means responsive to a difference between said mean and resonant frequency for
  • means tuned to resonance at a desired frequency for supplying carrier waves signal modulated in frequency about a mean frequency means including a pair of unilateral conducting devices for deriving from said carrier waves in-phase signal potentials proportional to a frequency modulations of said carrier waves, a pair of electric discharge devices having a common output circuit, means for applying said si for supplying carrier waves signal modulated in a frequency about a mean frequency, means including a-pair of unilateral conducting devices for deriving from said carrier waves in-phase signal potentials proportional within a predetermined band of frequencies to frequency modulations of said carrier waves, a pair of electric discharge devices having a common output circuit, means for supplying said signal potentials to said discharge devices respectively to control said output circuit, and means responsive to a difference between said mean and resonant frequencies for inversely controlling the conductivities of said electric discharge devices to reduce the transmission through the discharge device controlled by a non-proportional signal potential.
  • a receiver for electric oscillationameans tuned to resonance at a desired frequency for supplying carrier Waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coincidence of said mean .andresonant frequencies means including a pair of rectifier circuits for deriving from said carrier wave in-phase signal potentials proportional to signal modulations of said waves, a pair of parallel-connected electric discharge devices having a common output circuit, means for supplying one ,of said signal potentials to each of said devices to control said output circuit, and means responsive to a variation between said mean frequency and resonant frequencies for decreasing the conductivity of one or the other of said electric discharge devices in dependence upon the direction of said variation.
  • a receiver for electric oscillations means tunedto resonance at a desired frequency for supplying carrier waves signal modulated in frequency about a mean frequency, manually controllable means for effecting coincidence of said mean frequency and resonant frequencies, means including a pair of diode rectifier circuits for deriving from said carrier waves signal potentials including unidirectional components and in phase alternating components at signal frequency, said unidirectiona components being equal When said mean and re onant frequencies coincide, a pair of parallel-connected electric discharge devices having a common output circuit, means for supplying one of said alternating components of potential to each of said discharge devices to control said output circuit, and means differentially responsive to said unidirectional components of potential for controlling the conductivity of said discharge devices.
  • a receiver for electric oscillations means tuned to resonance at a desired frequency for supplying carrier waves signal modulated in frequency about a mean frequency, manually controllable means for effecting coincidence of said mean and resonant frequencies, means including a pair of rectifier circuits connected to said signal channel for deriving from said carrier waves signal potentials including unidirectional compo 'nents and in-phase alternating components at signal frequency, said unidirectional components being equal when said mean and resonant frequencies coincide and varyin in opposite senses upon relative displacement of said frequencies, a pair of electric discharge devices having a common output circuit, means including said in-phase components of signal potential for controlling said discharge devices, and means differentially responsive to said unidirectional components of potential and operable upon relative displacement ofsaid mean and resonant frequencies to bias toward cutoff the discharge device controlled by the signal potential having the greater unidirectional component and simultaneously to increase the conductivity of the other electric discharge device.
  • a tuned signal channel for supplying carrier waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coincidence of said mean frequency and the resonant frequency of said channel
  • a pair of diode rectifier circuits connected to said signal channel and including separate load resistors having a common point of fixed potential, said rectifier circuits being arranged to provide across adja cent portions of said load resistors signal potentials of opposite polarity with respect to said fixed potential, said signal potentials including in-phase alternating components at signal frequency and unidirectional components, a pair of parallel-connected electric discharge devices controlled by said alternating potentials and arranged jointly to supply a common output circuit, and means differentially responsive to the unidirectional potentials at electrically spaced points of said load resistors for controlling the conductivity of at least one of said discharge devices.
  • a tuned signal channel for supplying carrier waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coincidence of said mean frequency and the resonant frequency of said channel
  • a pair of diode rectifier circuits connected to said signal channel and including separate load resistors having a common point of fixedpotential, said rectifier circuits being arranged to provide across adjacent portions of said load resistors signal potentials of opposite polarity with respect to said fixed potential, said signal potentials including iii-phase alternating components at s gnal frequency and unidirectional components of equal magnitude when said mean and resonant frequencies coincide
  • a pair of parallel-connected electric discharge devices controlled by said signal potentials and arranged jointly to supply an output signal to a common output circuit.
  • a tuned signal channel for supplying carrier waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coincidence of said, mean frequency and the resonant frequency of said channel
  • a pair of diode rectifier circuits connected to said signal channel and including separate and equal load resistors having like intermediate points connected together and to a point of fixed potential
  • voltage dividing means connected between terminals of opposite polarity on separate load resistors to provide biasing potentials operable upon relative displacementof said mean and resonant frequencies to reduce the conductivity of the discharge device controlled by the signal potential having the greater unidirectional component and to increase the conduct
  • a signal channel for supplying carrier waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coincidence of said mean frequency and the resonant frequency of said channel
  • a pair of diode rectifier circuits connected to said channel and including separate load resistors having a, common point of fixed potential, said rectifier circuit being arranged to provide across adjacent portions of said load resistors signal potentials of opposite polarity with respect to said fixed potentials, said signal potentials including in-phase alternating component of said signal frequency and unidirectional component, a pair of parallel connected gridcontrolled electric discharge devices having a common output circuit, means for supplying said alternating components of signal potential to the control grids of said discharge devices to provide in said output circuit an amplified signal voltage, and means differentially responsive to said unidirectional components of potential for supplying to said control grids biasing potentials varying oppositely in response to variations between said mean and resonant'frequencies thereby inversely to control the conductivities of said discharge devices.
  • a tuned signal channel for supplying carrier waves signal modulated in frequency about a mean frequency
  • manually controllable means for effecting coirgdence of said mean frequency and the resonant frequency of said channel
  • a pair of diode rectifier circuits connected to said signal channel and including separate load resistors having a common point of fixed potential, said rectifier circuits being arranged to provide across adjacent portions of said load resistors signal potentials of opposite polarity with respect to said fixed potential, said signal potentials including in-phase alternating components at signal frequency and unidirectional components, a pair of parallel connected

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US484718A 1943-04-27 1943-04-27 Frequency modulation receiver Expired - Lifetime US2362806A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
CA432262A CA432262A (fr) 1943-04-27 Radiorecepteur a modulation des frequences
BE479154D BE479154A (fr) 1943-04-27
FR961086D FR961086A (fr) 1943-04-27
BE482547D BE482547A (fr) 1943-04-27
BE479153D BE479153A (fr) 1943-04-27
US484718A US2362806A (en) 1943-04-27 1943-04-27 Frequency modulation receiver
GB7770/44A GB594769A (en) 1943-04-27 1944-04-26 Improvements in and relating to frequency modulation receivers
US567110A US2422513A (en) 1943-04-27 1944-12-07 Frequency responsive network
FR938602D FR938602A (fr) 1943-04-27 1946-09-02 Perfectionnements aux récepteurs à modulation de fréquence

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US484718A US2362806A (en) 1943-04-27 1943-04-27 Frequency modulation receiver

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US2362806A true US2362806A (en) 1944-11-14

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US484718A Expired - Lifetime US2362806A (en) 1943-04-27 1943-04-27 Frequency modulation receiver

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US (1) US2362806A (fr)
BE (3) BE479154A (fr)
CA (1) CA432262A (fr)
FR (2) FR938602A (fr)
GB (1) GB594769A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2501120A (en) * 1945-04-26 1950-03-21 Rca Corp Frequency modulation receiver tuning aid
US2519890A (en) * 1944-12-09 1950-08-22 Rca Corp Angle modulated wave receiver
US2525359A (en) * 1946-04-04 1950-10-10 Rca Corp Frequency modulation receiver tuning aid
US2612602A (en) * 1948-11-19 1952-09-30 Gen Electric Noise suppression circuit
US2620439A (en) * 1947-11-05 1952-12-02 Gen Electric Noise balancing circuits

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107453346B (zh) * 2016-05-30 2022-03-18 中国电力科学研究院 一种适用于配电网重构的负荷曲线时段划分方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2519890A (en) * 1944-12-09 1950-08-22 Rca Corp Angle modulated wave receiver
US2501120A (en) * 1945-04-26 1950-03-21 Rca Corp Frequency modulation receiver tuning aid
US2525359A (en) * 1946-04-04 1950-10-10 Rca Corp Frequency modulation receiver tuning aid
US2620439A (en) * 1947-11-05 1952-12-02 Gen Electric Noise balancing circuits
US2612602A (en) * 1948-11-19 1952-09-30 Gen Electric Noise suppression circuit

Also Published As

Publication number Publication date
CA432262A (fr) 1946-01-01
BE479153A (fr)
FR938602A (fr) 1948-10-20
BE482547A (fr)
FR961086A (fr) 1950-05-03
GB594769A (en) 1947-11-19
BE479154A (fr)

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